Chronograph mechanism

ABSTRACT

In the drive train to the second hand of a stop watch is provided a gear mounted upon a rotating post to be moveable therewith through the intermediary of a slipping clutch means and brake means associated with the gear and operable to prevent rotation of the gear and hence the second hand and to allow rotation of the post.

United States Patent Lesser et al.

[ 1 Aug. 29, 1972 [541 CHRONOGRAPH MECHANISM [72] Inventors: Herbert F. Lesser, Ruhla; Manfred H. Schmeisser, Brotterode; Artur F.

21 Appl. No.: 58,329

[52] US. Cl... ....-.58/76, 58/77 [51] Int. Cl ..G04f 7/04 [58] Field of Search ..58/74-79 [56] References Cited UNITED STATES PATENTS 488,710 12/1892 Douglas .......58/76 490,123 1/ 1893 Nicolet ..58/77 7/1969 Bachmann ..58/76 FOREIGN PATENTS OR APPLICATIONS 218,932 l/l942 Switzerland ..58/74 698,763 10/ 1953 Great Britain ..58/74 Primary Examiner-Richard B. Wilkinson Assistant ExaminerGeorge H. Miller, Jr. Attarney-Nolte and Nolte [57] ABSTRACT In the drive train to the second hand of a stop watch is provided a gear mounted upon a rotating post to be moveable therewith through the intermediary of a slipping clutch means and brake means associated with the gear and operable to prevent rotation of the gear and hence the second hand and to allow rotation of the post.

8 Claims, 2 Drawing Figures CHRONOGRAPH MECHANISM The invention relates to a chronograph mechanism for watches having a sweep second hand arranged outside the flux of force, particularly for sports watches.

A chronograph is known the sweep second hand of which is arrangedoutside the flux of force. An auxiliary gear arranged on an intermediate gear shaft is provided with an adjustable clutch. The auxiliary gear drives a.

second pinion arranged in the minute wheel. Above the second pinion is arranged a brake gear and a zero setting heart-shaped cam with which is associated a brake lever operated by a ratchet wheel and a zero setting lever. The entire stopping mechanism is operated in known manner by only one crown. These watches as a rule operate satisfactorily but are expensive. Thus the production of the complicated ratchet wheel, which is absolutely necessary for the gearing.

sequence, results in great expense.

Due to the very sudden nature of the stopping, the ratchet wheel is subject to great mechanical stress. This leads after prolonged use to breakage of the teeth. The same holds true for the pawl driving the ratchet wheel.

A characteristic feature of certain other known chronographs or stop watches is that the drive of the second pinion is stopped or interrupted through a complicated gearing mechanism. By means of a lever mechanism controlled by a ratchet wheel the second pinion is stopped or disengaged from the driving gear.

These stopping devices are complicated mechanisms The arrangement according to the invention has the advantage that the clockwork is not blocked during the stopping process. In addition, the arrangement of the stopping mechanism permits addition stoppings. This way it is possible to use the watch also as a chronograph. With a few mechanical means a reliable chronograph mechanism has been'provided which can also be used for cheap watches. Compared to chronographs working by means of voluminous transmission mechanisms, the chronograph mechanism according to the invention has only eleven parts. This results in a considerable reduction in production costs.

The invention will now be described more fully by reference to a specific embodiment as illustrated in the drawings, in which:

FIG. 1 is a plan view of a stopping mechanism according to the invention; and

FIG. 2 is a detail along the section line A--A.

0n the back of upper plate 1 is arranged in known manner a sweep second hand running outside the flux of force which consists of an auxiliary or intermediate spring 10. The expanding spring 10 is compressed by a and are therefore highly susceptible to trouble. They are expensive. The assembly of these mechanisms requires considerable adjustments. Some parts, for example, the ratchet wheel, are subject to particularly great stress and must therefore be frequently replaced.

in watches without jewels, for example, Roskopf watches, are used simplified stopping mechanisms. These have a zero setting deviceand a yoke type lever mechanism which locks the balance wheel when the stopping push button is pressed. A disadvantage is that the movement in the watch is interrupted by the stopping process so that the time must be readjusted. This mechanism is so designed that addition stopping is not possible.

The object of the invention is to provide with a minimum expenditure for transmission parts a chronograph arrangement for sports watches the mechanism of which permits addition stopping.

According to the invention, a return spring, a return lever, a return core, an auxiliary gear with a slipping clutch, a slide with a locking spring, and a stopping push button are assembled to form a chronograph mechanism. Preferably such a mechanism consists only of eleven transmission elements. The stopping push button and the slide are associated to move in a common direction. The stopping push button with the slide and the locking spring'are arranged to act on the auxiliary wheel. The brake mechanism and the return mechanism can be operated independently of each other. The auxiliary wheel, an expanding spring and a disc form together a slipping clutch. The return lever is preferably mounted on a fastening screw for the upper plate. In the case is provided a notch for the stopping push button. The return spring has a short end engaged in a recess and a bent part engaged behind a hook. The hook is formed out of the upper plate.

disc 9 press fit on the pin 17. Under the second pinion 7 is arranged a return heart-shaped cam 6. The shaft 19 is held by the brake spring 4. Associated with the return heart-shaped cam 6 is a known return lever 2 which is mounted on a fastening'screw 5 which serves at the same time to fasten the upper plate 1. Engaging the return lever 2 is a zero setting button 13, which is mounted in the case ring 15 in the proximity of the winding crown l8 and which is under the action of a return spring 3 mounted on the upper plate 1. The return spring 3 is mounted with its short end in a recess 20 and with its bent part behind a hook 21. The hook 21 is formed from the upper plate 1. Arranged symmetrically to the zero setting button 13 is a stopping push button 14, mounted likewise in the case ring 15 and which presses against a slide 11. The slide 11 is mounted in an oblong slot of the upper plate 1 and has on its side facing the auxiliary wheel 8 a locking spring 12.- Advantageously the stopping push button 14 is provided with a notch or detent.

The method of operation of the mechanism is as follows:

If a certain event has to be timed, the stopping push button 14 is released upwards. The locking spring 12 releases the toothing of the auxiliary gear 8 and the second hand begins to run. When the pushbutton 14 is pressed, the locking spring 12 engages the toothing of the auxiliary wheel 8 and brakes the latter so that the second hand is stopped. The slipping clutch of the auxiliary wheel 8 permits movement of the clock mechanism without any major load. For the zero setting of the second hand the zero setting button 13 is pressed down. The return lever 2 moves the return heart-shaped earn 6 with the second hand back into its starting position. For addition stopping. the stopping push button 14 is released without setting the second hand to zero.

What is claimed is:

1. In a watch comprising a casing, drive means located in the casing, a first gear in driven association with the drive means, a second gear engaging the first gear, a minute hand in driven association with the first gear and a second hand in driven association with the second gear, a chronograph mechanism comprising braking means, means operable from outside the casing for reversibly moving the braking means from a position braking the second gear to a position permitting the second gear to rotate, the braking means comprising an elongated member mounted in the casing for movement parallel to the length of the member and having one end fixed to the means for moving the braking means and a locking spring fixed to the other end of the member and extending transversely of the length of the member so as to engage the teeth of the second gear when the braking means is in the braking position, a shaft on which the second gear is rotatably mounted, and a slip clutch interconnecting the shaft and the second gear, the slip clutch being adapted to permit the shaft to rotate when the second gear is braked and to rotate the second gear with the shaft when the second gear is not braked.

2. A chronograph mechanism according to claim 1, in which the braking spring extends substantially perpendicularly to the length of the elongated member.

3. A chronograph mechanism as claimed in claim 1 wherein said slip clutch comprises a collet fixed to the shaft for rotation therewith and resilient means urging the second gear into frictional engagement with the collet.

4. A chronograph mechanism according to claim 3, in which the braking spring extends substantially perpendicularly to the length of the elongated member.

5. In a watch a chronograph mechanism according to claim 1, further comprising a cam mounted for rotation with the first gear, lever means reversibly removable from a position spaced from the cam to positions engaging and rotating the cam to a cam position in which the first gear has been so rotated as to have rotated the second gear to the zero position of the second hand.

6. A chronograph mechanism according to claim 5, in which the braking spring extends substantially perpendicularly. to the length of the elongated member.

7. A chronograph mechanism as claimed in claim 5 wherein said slip clutch comprises a collet fixed to the shaft for rotation therewith and resilient means urging the second gear into frictional engagement with the collet.

8. A chronograph mechanism according to claim 7, in which the braking spring extends substantially perpendicularly to the length of the elongated member. 

1. In a watch comprising a casing, drive means located in the casing, a first gear in driven association with the drive means, a second gear engaging the first gear, a minute hand in driven association with the first gear and a second hand in driven association with the second gear, a chronograph mechanism comprising braking means, means operable from outside the casing for reversibly moving the braking means from a position braking the second gear to a position permItting the second gear to rotate, the braking means comprising an elongated member mounted in the casing for movement parallel to the length of the member and having one end fixed to the means for moving the braking means and a locking spring fixed to the other end of the member and extending transversely of the length of the member so as to engage the teeth of the second gear when the braking means is in the braking position, a shaft on which the second gear is rotatably mounted, and a slip clutch interconnecting the shaft and the second gear, the slip clutch being adapted to permit the shaft to rotate when the second gear is braked and to rotate the second gear with the shaft when the second gear is not braked.
 2. A chronograph mechanism according to claim 1, in which the braking spring extends substantially perpendicularly to the length of the elongated member.
 3. A chronograph mechanism as claimed in claim 1 wherein said slip clutch comprises a collet fixed to the shaft for rotation therewith and resilient means urging the second gear into frictional engagement with the collet.
 4. A chronograph mechanism according to claim 3, in which the braking spring extends substantially perpendicularly to the length of the elongated member.
 5. In a watch a chronograph mechanism according to claim 1, further comprising a cam mounted for rotation with the first gear, lever means reversibly removable from a position spaced from the cam to positions engaging and rotating the cam to a cam position in which the first gear has been so rotated as to have rotated the second gear to the zero position of the second hand.
 6. A chronograph mechanism according to claim 5, in which the braking spring extends substantially perpendicularly to the length of the elongated member.
 7. A chronograph mechanism as claimed in claim 5 wherein said slip clutch comprises a collet fixed to the shaft for rotation therewith and resilient means urging the second gear into frictional engagement with the collet.
 8. A chronograph mechanism according to claim 7, in which the braking spring extends substantially perpendicularly to the length of the elongated member. 